Issue porting From Qt4.1.x To Qt4.4.1

Hello

I am having an issue where a DLL compiled under Qt4.1.5 does not work with the Qt4.4.1 libraries. I have 2 dll's the first is not under my control, it is compiled with Qt4.1.5. The second is a common dll my diagrams use, this is also compiled in Qt4.1.5 and linked against the previous dll. the third object i have is an exe file that uses my common and by extension the other DLL. Now on the test system, we normally use Qt4.1.5 libraries, but for this case i placed Qt4.4.1 libraries in the directory where my executable is and changed the path accordingly. when i loaded the exe the first dll found everything EXCEPT some Symbols for QVector or QPoint.

The error message was as such:
The procedure entry point ??4?$QVector@VQPoint@@@@QAEAAV0@ABV0@@Z could not be located in the dynamic link library QtGui4.dll

does anyone have any ideas as to how this problem can be solved or what is causing it?